Evaluation of Antifungal Activity of Antimicrobial Agents on Cheddar Cheese By Kuorwel K. Kuorwel, 1 Marlene J. Cran, 2 * Kees Sonneveld, 3 Joseph Miltz 4 and Stephen W. Bigger 1 1 School of Engineering and Science, Victoria University, PO Box 14428, Melbourne 8001, Australia 2 Institute for Sustainability and Innovation, Victoria University, PO Box 14428, Melbourne 8001, Australia 3 KS PackExpert & Associates, PO Box 399, Mansfield, Victoria 3724, Australia 4 Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel The antifungal activity against Aspergillus niger of the antimicrobial (AM) agents linalool, carvacrol and thymol incorporated in the coatings of starch-based films was investigated. The activity was initially deter- mined on a solid medium using the modified microatmosphere method and then examined on Cheddar cheese. On the solid media, all the AM films demonstrated a significant inhibitory effect against A. niger growth. The inhibitory effect of the AM films containing 2.38% (w/w) AM agents is reflected by the colony diameters that were 29.3, 25.4 and 21.3 mm for linalool, carvacrol and thymol, respectively, at 25  C after 7 days incubation compared with the control sample where the colony diameter was 85.3 mm. The AM films containing 2.38% (w/w) linalool, carvacrol or thymol reduced the population of A. niger on the surface of Cheddar cheese by 1.8, 2.0 and 2.2 log CFU/g, respectively, after 35 days of storage at 15  C. The results suggest that starch-based film coated with an AM agent has the potential for being used as a fungicidal packaging system. Copyright © 2012 John Wiley & Sons, Ltd. Received 29 November 2011; Revised 13 July 2012; Accepted 24 September 2012 KEY WORDS: antimicrobial packaging system; starch-based films; antimicrobial agent; carvacrol; thymol; linalool; Aspergillus niger INTRODUCTION There are many different forms of antimicrobial (AM) agents that can potentially be used to inhibit microbial growth in food products. 1 The range of AM agents that are known to possess a strong AM activity includes synthetic organic acids, fungicides, alcohols and antibiotics. 2 However, consumer preference for the use of natural AM agents over synthetic AM agents has increased recently. 3 Beyond being natural, the rationale for the use of active constituents derived from various essential oils (EOs) such as linalool, carvacrol and thymol derived from basil, oregano and thyme, respectively, is their broad AM spectrum against different pathogenic and spoilage microorganisms including Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Saccharomyces cerevisiae, Candida albicans, Aspergillus niger, Alternaria alternata, Aspergillus flavus and Penicillium roqueforti. 4–9 Furthermore, some of the EOs and/or their active components are considered to be safe and have the ‘generally recognized as safe’ status as designated by the American Food and Drug Administration. 10 Moreover, thymol and carvacrol are approved food additives, particularly as flavouring agents, in Europe 11 and the USA. 10 * Correspondence to: Marlene J. Cran, Institute for Sustainability and Innovation, Victoria University, PO Box 14428, Melbourne 8001, Australia. E-mail: marlene.cran@vu.edu.au PACKAGING TECHNOLOGY AND SCIENCE Packag. Technol. Sci. 2014; 27: 49–58 Published online 11 October 2012 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/pts.2003 Copyright © 2012 John Wiley & Sons, Ltd.